Torque wrench



' Dec. 2, 1969 H. G. SCHUBERT 3,481,193

TORQUE WRENCH Filed July 27. 1967 40 I 28 as 34 INVENTOR. HANSG.SCHUBERT ATTORNEYS United States Patent 3,481,193 TORQUE WRENCH HansG. Schubert, 1426 Rose Garden Lane, San Jose, Calif. 95129 Filed July27, 1967, Ser. No. 658,015

Int. Cl. G011 /24; B25b 23/14 US. Cl. 73-139 5 Claims ABSTRACT OF THEDISCLOSURE A torque measuring wrench in which the relative angulardisplacement of the opposite ends of a torque-transmitting member istransmitted to a torque-indicating arm pivotally mounted on the memberand extending along the length of the member.

This invention relates to torque wrenches and, more particularly, to animproved torque-measuring wrench in which the eifect of applied torqueto the wrench is substantially magnified in order to yield an accuratereading of applied torque.

Torque-measuring wrenches are well-known in the art. The usual torquewrench comprises an elongated arm having a standard square drive elementat one end. The torque-indicating means associated with the elongatedarm may comprise gearing or a rack and pinion arrangement or even springsteel strips, the purpose of which is to move a pointer to indicate theapplied torque.

Variations of such torque-measuring apparatus are known in which theindicating device is separated from the handle. Such variations ofteninvolve gearing or other complex indicating linkages combined with alarge dial face and pointer. The dial face and pointer usually extendlaterally from the torque device, thus making the entire arrangementclumsy to handle and easily damaged.

The present invention is designed to provide a compact, easily used,accurate torque-measuring wrench. The present construction utilizes anovel elongated torque-indicating member which substantially magnifiesthe relative angular displacement of the opposite ends of thetorquetransmitting member or rod upon which the torqueindicating memberis carried.

In its narrower scope, the present invention includes atorque-indicating collar which is moved by the torqueindicating memberand which includes a calibrated scale marked upon it for a directreading of applied torque. The preferred embodiment combines atorque-transmitting rod, a collar rotatably mounted at one end of thetorque rod, an elongate torque-indicating member engaged with the collarand pivotally mounted at the opposite end of the torque rod and an armsecured to the torque rod near the collar and extending along thetorque-transmitting member and having its opposite end coupled to thetorqueindicating member for moving the torque-indicating member and thecollar coincidentally with angular displacement of the opposite ends ofthe torque rod resulting from the application of torque thereto.

In the drawing, FIG. 1 is a front elevational view of the torque wrenchin partial section and FIG. 2 is another elevational view of the wrenchalso in partial section, taken along the line 22 of FIG. 1.

FIG. 3 is a detail of the work-engaging end of the wrench.

Referring now more particularly to the drawing in which similarcharacters of reference represent corresponding parts in each of theseveral views, the torque wrench is shown generally in FIG. 1. Thetorque-transmitting member or rod has a standard square drive element 12on one end adapted to engage a wrench socket in order to exert torque ona bolt head or other work (not 3,481,193 Patented Dec. 2, 1969 'iceshown). The opposite end is formed with a square recess 14, adapted toreceive the drive element of a torquetransmitting handle. The drawingshows a universal joint drive 16 received in the recess 14. Atorque-transmitting handle would be then engaged in the universal jointfor the application of torque to the wrench.

The recess 14 is formed in a cylindrical shoulder 18, on one end of thetorque-transmitting rod 10. Rotatably mounted on the shoulder 18 is atorque-indicating collar 20 formed with a tab 22 having a radiallyoriented slot 24 therein, into which is engaged one end of thetorqueindicating link 26.

The opposite end of the link 26 is formed with an enlarged base 28. Thebase 28 is mounted on a pivot 30, the pivot being aifixed near the workengaging element 12, at the end of the torque-transmitting rod 10.

A rigid arm 32 is secured to the shoulder 18. The arm 32 extends alongthe torque-transmitting rod 10, terminating near the work engagingelement 12. The end 34 of the arm 32 is positioned closely adjacent thepivot 30 although there is clearance between the end 34 of the arm andthe lower shoulder 36 of the torque transmitting rod 10 to which thepivot 30 is afiixed.

The end 34 of the arm 32 is provided with a ball 38 suitably mounted ona post 40. The ball is received within a complementary spherical recesswithin the base 28 of the indicating link 26.

As may be noted in FIG. 2, the center of the ball 38 received within therecess is offset from the axis of the pivot 30. The distance between thecenter of the ball and the pivot axis is quite small compared with thelength of the link 26. Therefore, a relatively small angulardisplacement between the ends of the torque rod 10 is substantiallymagnified. This results in highly accurate readings of the appliedtorque.

In order to yield the most accurate indication of torque, indicatormarks and scales are provided to show relative rotation of the shoulder18 and the collar 20. Scale calibrations 42 are marked axially along thecircumference of shoulder 18 and radially on the collar 20.Corresponding indicator markings 44 are cut into both the shoulder andthe collar. The use of calibration scales and indicator markings on boththe shoulder 18 and the collar 20 permits the user to note the readingsfrom whatever position the scales are observed and no matter whatposition the torque handle may have with respect to the drive end of thetorque wrench.

In FIG. 3 an alternate embodiment of the connection between the end 34of the arm 32 and the link 26 is shown. The alternate comprises a pairof ball joints 46 one of which is affixed to the end 34 of the arm andthe other to the end 48 of the torque-indicating link 26.

In operation, a wrench socket is afiixed to the drive element 12. Thesocket will be suitable for the particular work piece such as a bolt,spark plug or the like. A drive handle (not separately shown) isattached to the wrench by placing its drive element in the recess 14 orin the recess of the universal joint 16 when the universal joint is inplace. As torque is applied and the work piece tightened, there will beangular displacement between the driving and driven ends of the torquerod 10. This relative angular movement will cause the relative movementof the pivot 30 and the spherical portion 38 of the bolt joint as well.This in turn will cause movement of the link 36 which will itself rotatethe collar 20.

The calibrations may be chosen so that a direct reading in foot-poundsmay be made. The distance between the center of the ball 38 and the axisof the pivot 30 heretofore described varies according to the size of theparticular torque wrench. Should a substantial magnification of theangular displacement of the ends of the torquetransmitting rod 10 bedesired, it is possible to decrease the distance between the center ofthe ball 38 and the axis of the pivot 30. Decreasing this distance willcause correspondingly greater rotation of the collar 20 for a directreading of the applied torque. A light spring (not separately shown) isconnected between the collar 20 and the torque rod 10 in order to reduceany play in the collar movement and make for more accurate readings.

These and other modifications of my invention may be practiced, it beingunderstood that the form of my invention as described above is to betaken as a preferred example of the same. Such description has been byway of illustration and example for purposes of clarity ofunderstanding. Various changes and modifications may be made withoutdeparting from the spirit and scope of my invention.

What is claimed is:

1. A torque-measuring wrench comprising: a torquetransmitting memberhaving a first end adapted for work engagement and a second end adaptedfor engagement by a force transmitting tool; an arm secured to saidsecond end and extended adjacent to and free from said first end; acollar rotatably mounted adjacent said second end; a link pivotallymounted on the torque member adjacent said first end and engaged withsaid collar; and a connection between the link and the free end of thearm for moving the link and thereby the collar when there is relativemovement between the torque member and the free end of the arm.

2. The wrench of claim 1 and wherein the collar has a tab securedthereto, said tab having a slot wherein the link is engaged; and a scalemarked on the collar and on the second end of the torque member, thescale calibrated so that upon application of torque to the member theposition of the collar relative to the second end indicates the amountof applied torque.

3. The wrench of claim 1 and wherein the connection includes a balljoint, the center of rotation of said joint offset from the pivotalmounting of the link.

4. A torque measuring device comprising a torquetransmitting rod havinga work engaging end and a forcetransmitting element at the other end, .atorque-indicating member extending along the torque rod, means forpivotally mounting said torque-indicating member at said work engagingend, and means for transmitting relative angu lar movement of theopposite ends of said torquetransmitting rod about the axis of said rodto said indicating member, said transmitting means including aconnection between said force-transmitting element and said indicatingmember adjacent said pivotal mounting means.

5. The device of claim 4 and wherein said angular movement transmittingmeans comprises: a frame extending along said torque rod with one end ofsaid frame secured to the torque-transmitting rod adjacent theforcetransmitting element, and the other end of said frame free from andpositioned close to said work engaging end and a coupling secured to thefree end of said frame and engaged with the torque-indicating member ata location spaced from said pivotal mounting means.

References Cited UNITED STATES PATENTS 2,404,029 7/1946 Birk 73-1392,934,946 5/1960 Engquist 73---139 FOREIGN PATENTS 528,929 7/1931Germany. 629,132 9/ 1949 Great Britain.

CHARLES A. RUEHL, Primary Examiner

